Left ventricle diastolic dysfunction (LVDD) is associated with resistant hypertension. In addition, brain natriuretic peptide (BNP) levels are elevated when LVDD is present. It has been shown that phosphodiesterase-5 (PDE5) inhibition improves left ventricle diastolic function in hypertensive rats, despite any difference in blood pressure levels. Also, left ventricle diastolic function enhancement reduces BNP concentration in hypertensive patients. However, it is unknown if these effects exists in humans with resistant hypertension. Therefore, this study was developed to evaluate if the use of a PDE5 inhibitor (tadalafil) for 2 weeks improves LVDD and its effects in BNP levels in resistant hypertensive patients.